Field of the Disclosure
The present disclosure relates to an image processing technique for handling compressed image data.
Description of the Related Art
An image processing apparatus represented by a multi function peripheral (MFP) includes a plurality of processing units such as a drawing processing unit, a compression processing unit, and a decompression processing unit. In the plurality of processing units, a pipeline processing configuration in which output data from one processing unit is input to another processing unit has been adopted. In the pipeline processing, when a local memory is provided as a buffer between the processing unit from which data is to be output and the processing unit to which data is to be input, even if there occurs a difference between the respective processing speeds of the processing units, the difference is absorbed. Japanese Patent Application Laid-Open No. 2014-53822 discusses a technique for changing the capacity of the local memory depending on whether image data to be processed is in color or in monochrome.
In the image processing apparatus, a series of processing, described below, is performed. When the drawing processing unit performs drawing processing based on drawing data to generate image data in a bit map format, if the drawing data includes compressed image data, the decompression processing unit decompresses the compressed image data and stores the decompressed image data in a first local memory. The drawing processing unit performs drawing processing using the decompressed image data stored in the first local memory. At this time, the drawing processing unit stores image data generated by the drawing processing in a second local memory. Then, the compression processing unit compresses the image data stored in the second local memory using an encoding method such as Joint Photographic Experts Group (JPEG) encoding. At this time, the compression processing unit stores the compressed image data in a main memory such as a dynamic random access memory (DRAM).
Conventionally, a capacity of the first local memory to be allocated has been fixed regardless of whether drawing data includes compressed image data. Therefore, if the drawing data does not include the compressed image data, the first local memory is not used. Thus, memory resources have not been efficiently used.